(40r) Synthesis, Characterization and Application of Metal Organic Framework with One or Two Metal Sites for CO2 Adsorption

Crystalline metal-organic frameworks (MOFs) have recently emerged as potential candidate adsorbent for CO₂ capture applications mainly due to their high surface area and tailorable structure. The presence of open metal sites in some MOFs strengthens their adsorption sites, which are favorable for CO₂ capture and CO₂ separation. The objective of this study is to compare the performance of five different MOFs for CO₂ capture. Specifically, single metal (Mg, Co, and Zn-MOF-74 and Cu-MOF-199) and two metal (Mg-Co-MOF-74) MOFs were synthesized and characterized using X-ray diffraction (XRD) patterns, surface and bulk elemental analysis (XPS and CHN), scanning electron microscopy (SEM), CO₂ adsorption isotherm. XRD and XPS showed that the structures of the samples were in a good agreement with previous reports and all metal cations were incorporated within the MOF structure. The XRD pattern for Mg-Co-MOF-74 was identical to that of single metal MOF74. Higher affinity was found for Mg-Co-MOF-74 compared to other MOFs, based on Henry’s law constant. CO₂ adsorption capacity of 5.6, 4.0, 2.2, 4.9, and 6.4 mmol/g were obtained for Mg, Co, and Zn-MOF-74, Cu-MOF-199, and Mg-Co-MOF-74, respectively, indicating higher adsorption capacity of two metal MOF towards CO₂ compared to single metal MOFs. The higher affinity and adsorption capacity of Mg-Co-MOF-74 suggests that it is the most favorable MOF, among the five tested MOFs, for CO₂ capture application.